I guess what some fear is actually that they could use the low fees currently to publish OP_RETURN stuff for 1 or 2 sat/vByte and (together with consolidation txes from exchanges) fill up the "low fee slots" every day. The "problem" here is that some of these NFT use cases have no urgency to transact, they can use the lowest fee periods of the week. And thus they can price out the regular users who want to make a payment and want it to be confirmed in less than an hour or so.

Those users wanting to publish a NFT in a certain block of course would have to pay higher fees.

But my point is another one, I don't know how much of the discussion here you read. But basically, the OP_RETURN method is not cheaper than the Taproot method Ordinals uses, and thus would not lead to additional incentives for NFTs. And thus there's also no mechanism to price out other users, merely by the effects of this change.

The only possible mechanism for a fee surge is a new fad based on OP_RETURN NFTs, for whatever reason. Often fads only appear "because something is new", and that could be the case here as part of the "social" effect I mentioned. I think it's quite unlikely though. The NFT hype has consolidated a lot, and for the (probably very small) public who wants to buy "a NFT on the OG Bitcoin chain!!!!!" there are a large number of NFTs from the Ordinals wave waiting for buyers.

There can be scarcity of NFTs during hype periods. Scarcity exists always if there are more buyers wanting to buy for a certain price than sellers (demand > supply). That happens if there's a fad going on and there are more "believers" than supply. Even if the fad is short, it's still scarcity. And as you wrote correctly it's often related to a "feeling" of "community" like in the case of these collections.